Place butter into a large mixing bowl and stir in sugar until well combined. Add egg, bananas and sour cream mixing until well combined. Stir in flour, baking soda, baking powder, salt and marshmallow bits until combined. Pour half of the batter into prepared loaf pan. Layer with graham crackers then Hershey Bars. Top with remaining banana bread batter spreading evenly then bake for 50-55 minutes or until baked through. Let cool for 30 minutes then remove from pan and let cool completely. Cut into slices and serve! Garnish top of bread with additional marshmallow bits if desired.